Measuring the CP nature of the Yukawa coupling between the Higgs boson and tau leptons

The first direct measurement of the CP nature of the Yukawa coupling between the Higgs boson and tau leptons is presented. The data used in this analysis were collected in proton-proton collisions recorded by the CMS experiment at the LHC and correspond to a total integrated luminosity of 137/fb and a centre-of-mass energy of √s=13 TeV. CP-sensitive observables are reconstructed using the angular correlation between the decay planes of tau leptons in the H → τ+τ− decay. The observed (expected) value of the effective mixing angle between the CP-even and CP-odd couplings is found to be −1±19◦ (0±21◦) at 68% confidence level. The result is in agreement with the Standard Model predictions within uncertainties and disfavours a pure CP-odd coupling at 3.0 σ confidence level.Open Acces